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What Is Noise Factor? How Noise Factor Is Important In LNA?

Modern receiving systems like satellites, mobile phones, radio, TV set-top boxes, and other deceives that operate in low coverage areas need to capture and process signals that are weak in nature.

The major challenge for these devices to catch these weak signals is the amount of noise associated with it. This can be understood by a parameter called Noise Factor.

In this article, you'll get a clear insight into Low Noise Amplifier. How noise factor is important in LNA? The noise factor is an important parameter for the Radio Frequency systems and is used for Radio Frequency Amplifiers and Radio Frequency receiver designs.

The noise factor is mathematically the ratio of effective input noise power to noise input from source resistance.

NF = effective input from source power ÷ noise input from a source resistance

Let's try to know What is noise factor. The noise factor is a measure of the degradation of the signal-to-noise ratio of a device. The noise factor is also referred to as the noise figure.

The components of a signal chain basically cause the signal-to-noise ratio (SNR). SNR is the number used for the specification of the performance of an amplifier or a radio receiver. The noise factor is an essential element of the RF circuit design of any radio receiver and is used in association with radio sensitivity.

The signal-to-noise ratio at the output is always lower as compared to the signal-to-noise ratio at the input, and that's why the value of the noise factor is always less than 1. The noise factor for a device is measured by the formula, which is normally represented by the formula


Sin = The Signal level at input

Nin = The Noise level at input

Sout = TheSignal level at output

Nout = The Noise level at output

This Elite RF LLC Noise factor describes the level of noise generated by a Radio Frequency system or device. The lower the noise factor of a device, the better its performance.

Noise factor and Noise figure are quite similar, and both of them can be interchangeable. While the Noise factor gives a mathematical representation of the degradation value, the noise figure describes the same in a logarithmic scale. The noise factor formula is

However, the units of noise factor and noise figure are different. The noise factor is measured in linear units, while the noise figure is measured in decibel units.

If the noise factor is not controlled, then we need to increase the signal power or the size of the antenna. However, it is very costly to increase the size of the signal power, whereas reducing the noise factor is cheaper to achieve the same signal-to-noise ratio. Hence it is a major importance of noise factor.

For example, a reduction in the noise factor of a low noise amplifier (LNA) has the same amount of output as incredible the diameter of the antenna by almost 40%. This makes the noise factor reduction much more beneficial than increasing the signal power.

The output ratio S/N of the receiver depends on two factors, the S/N ratio of input and the noise factor. The input S/N ratio depends on various parameters like the transmitted power, atmospheric transmission coefficient, transmitter antenna gain, receiver antenna gain, and the noise factor of the receiver.

For this reason, lowering the noise factor of the receiver will have the same effect on the output S/N ratio as improving any of these quantities. Hence it becomes an important part of the transmitter design to control the noise factor.

How noise factor is important in LNA or LNA is a type of electronic amplifier used to amplify a low-power signal without degrading its SNR ratio. LNA is actually the first stage of a receiver system.

The noise factor and the noise figure of the system are affected by the noise gain performance of the LNA. Initially, the active device of the LNA is matched with the input of the system to achieve optimum noise conditions.

The work of such an amplifier is to increase both the signal and the noise of the input, however, in doing so, the amplifier also increases an additional noise. This is where LNA is used, as it is used to minimize such additional noise with the help of low-noise components, circuit topologies, and operating points.

Normally an LNA supplies a power gain of 100 units (20 decibels) and decreases the signal-to-noise ratio by around 3 decibels. LNAs are commonly found in radio communication systems, electronic test equipment, and medical instruments.

This type of low noise amplifier is commonly found in all receivers. It plays a major role in boosting the power of the received signal to such a level that it is above the noise factor, and then it can be easily used for further processing. For this reason, the LNA noise factor directly limits the receiver's sensitivity.

Elite RF LLC is a firm that provides all types of solutions for RF Amplifier, Test Equipment offerings, and all other standard products. We specialize in the state-of-the-art Radio Frequency and microwave communication systems.

All our products and RF services are customs designed to meet the demands of wireless infrastructure applications. Telecommunications, radio communication, satellites, set-top boxes, and other information as well, can be shared with minimum distraction.

Noise degradation has always been our primary focus in all the products that have made the agency a leading corporation in this sector.